Stroke is the third leading cause of death and a major cause of long-term disability in the United States. Most clinical trials of acute stroke therapy have failed, underscoring the need to identify new therapeutic targets and develop effective therapies to reduce brain damage. Our broad goal in this proposal is to unravel the molecular pathways governing the detrimental effect of neuroinflammation and specifically microglia in stroke injury. Knowledge gained will help identify new drug targets for stroke therapy. The central hypothesis is that microglia are activated during ischemia and contribute to the development of injury. Two aspects of this microglia-mediated injury are explored, the depletion of epoxyeicosatrienoic acid (EET) during ischemia, which increases neuronal death, as well as the inactivation of EET after ischemia, which increases microglial activation and further exacerbates injury. In Specific Aim 1, we will determine whether microglia deplete EET through CD36-mediated uptake and whether EET deficiency contributes to neuronal death after ischemia. In Aim 2, we will determine whether depletion of EET by microglia contributes to stroke injury in vivo. In Aim 3, we will test whether blocking EET inactivation in microglia reduces microglial activation and microglia-mediated neuronal death. Finally, in Aim 4, we will investigate whether inhibition of EET-inactivating soluble epoxide hydrolase in microglia blocks microglial activation after stroke in vivo and reduces stroke injury. The overarching goals are to develop and characterize new experimental approaches to the clinical problem of stroke, specifically to understand the contribution of microglia to stroke pathology as well as use the increasing understanding of microglia/neuronal interplay and microglia-mediated injury to define new therapeutic targets and approaches for acute stroke. The experiments will help characterize the role of epoxyeicosatrienoic acid in microglia activation and microglia-mediated injury after stroke. The candidate is an anesthesiologist and neurointensivist with a strong research background studying ischemic brain injury. The candidate's institution provides a supportive and collaborative environment that is ideally suited to fostering the continued academic and scientific growth of a newly independent investigator. The additional expertise acquired through the proposed experiments will foster the candidate's scientific development and growth as an independent researcher. Evidence gathered in these studies will provide the base for a successful future R01 application.